In recent years, with increasing interest in environmental pollution due to various toxic materials contained in exhaust gas generated upon combustion of heavy oil, marine diesel oil (MDO), and the like used as fuel for various ship engines, regulation has been intensified with regard to ship engines using heavy oil and the like as fuel, thereby causing increase in costs to comply with such regulations.
Accordingly, development of ships using clean gas fuel such as LNG, LPG, CNG or DME has been suggested and achieved in addition to the prevention or minimization of use of fuel oil such as heavy oil or MDO.
Particularly, an M-type electronically controlled gas injection (MEGI) engine uses liquefied natural gas as fuel, and includes a high pressure pump and a high pressure evaporator in order to achieve a required high pressure gas supply (200-300 bar).
Fuel gas is generally stored in a liquid state in a fuel gas tank at low temperature. The fuel gas tank has a larger size and a heavier weight than diesel oil tanks. In order to supply fuel gas from the fuel gas tank to an engine, a high pressure pump and a high pressure evaporator are required. These devices are disposed in a fuel gas supply (FGS) room. Thus, it is an important issue to determine suitable locations of the fuel gas tank and the FGS room in a ship in order to achieve efficient use of a space in the ship.
In addition, the ship is provided with a bunkering manifold which receives fuel gas, and a vent riser which acts as a vent hole through which boil-off gas (BOG) is discharged from the fuel gas tank and the FGS room in an emergency. Since the bunkering manifold acts as a device for receiving the fuel gas, and the vent riser discharges BOG, both devices are exposed to a risk of explosion. Therefore, it is important to determine suitable locations of the bunkering manifold and the vent riser within the ship in order to facilitate supply of fuel gas while reducing the risk of explosion.